The present invention relates to compositions which include water, alkali metal hydroxide components, and chelating components, and to methods of producing such compositions. More particularly, the present invention relates to compositions, for example, solutions, comprising water, alkali metal hydroxide components and chelating components which have increased solubility or storage stability, and to methods of producing such compositions.
Highly alkaline liquid compositions including one or more chelating agents are commercially useful. For example, such compositions are useful as alkali builders in the laundry industry. However, such chelating component-containing, alkaline compositions, for example, made alkaline by an alkali metal hydroxide component, such as sodium hydroxide, tend to produce crystals or other solid materials, for example, crystals including the chelating component, in the compositions after a period of storage. It is desirable, in a number of applications, that these alkaline compositions be provided for use as liquid solutions, that is without containing crystals and/or other solid materials. Thus, the concentration of the alkaline metal hydroxide component and/or the chelating component in such compositions has been limited because of the limited solubility of these components in the compositions.
It is known that enhanced solubility, for example, of the chelating component, can be obtained by using a combination of sodium hydroxide and potassium hydroxide in such alkaline compositions. However, the combination of sodium hydroxide and potassium hydroxide is substantially more expensive, and therefore less attractive, than using a single alkali metal hydroxide, for example, sodium hydroxide.
Thus, there is a continuing need to provide alkaline, chelating component-containing compositions which have increased solubility so as to reduce the cost of transporting and storing the product while, at the same time, providing a very effective form, in particular a soluble form, of the composition for use by the final consumer of the composition.